Getter assembly



United States Patent GETTER ASSEMBLY Aden J. King, Syracuse, N. Y., assignor to King Laboratories Inc., Syracuse, N. Y., a corporation of New York No Drawing. Application May 12, 1952, Serial No. 287,421

5 Claims. (Cl. 2060.4)

This invention relates to getters employed to produce high vacuum in electronic tubes, and has to do more particularly to the production of high vacuum in electronic tubes of the cathode-ray type.

In present practice, after the tubes have been assembled and the envelope sealed, the major portion of the gas in the tubes is removed by mechanical and difiusion pumps. The residual gas is further reduced by the action of a getter. Essentially, the getter assembly consists of barium, or a barium alloy, arranged in a metallic support. On the application of heat, usually by means of a high frequency bombarder, the support is heated to a temperature sufiiciently high to vaporize the barium which acts as a getter or clean-up agent by combining with the residual gas and thereby produces a very high vacuum within the tube. In this process, there are instances, particularly where an alloy of barium is used in the assembly, where the non-volatile residue of the getter composition remaining after vaporizataion of the barium may itself be magnetic, or it may combine with the material of the support to form a magnetic alloy.

In certain types of cathode-ray tubes, it is either essential, or highly desirable, that no magnetic materials be present within the tube, particularly in positions where a magnetic field my cause distortion of the electronic beam.

This invention has as an object a getter assembly which, after vaporization of the barium, will not leave any magnetic residue, or form a magnetic alloy with ltalie material used in the support element of the assem- The getter assembly used to accomplish this result consists of a getter composition containing barium, aluminum, and one or more metals of the fourth group elements such as titanium or zirconium contained in a low iron content, nickel chrome alloy support. As an example, a getter composition containing 35% barium, 40% aluminum, and 25% titanium contained in a low iron content, nickel chrome alloy support, yielded a residue which, after vaporization of the barium, was itself non-magnetic and which combined with the supporting metal to form an alloy which was also essentially nonmagnetic.

As a further example, a getter composition containing 2,706,554 Patented Apr. 19, 1955 approximately 35% barium, 40% aluminum and 25% zirconium, likewise gave a non-magnetic residue and formed essentially a non-magnetic alloy with the support.

I have found that getter compositions containing titanium or zirconium will function produce the nonmagnetic residue when they are compounded within the following range:

Per cent Barium 30-40 Aluminum 30-40 Titanium or zirconium 10-40 The composition may also contain other metals, such as nickel, chromium, copper or manganese, as additives to improve the fabricating or physical characteristics of the composition. For example, a getter composition consisting of 31% barium, 31% aluminum, 17% titanium, 14% nickel, and 7% chromium, functions to efficiently evacuate the tube and leaves no magnetic residue and forms no alloy with the support which has magnetic characteristics.

What I claim is:

1. A getter assembly comprising a support formed of low iron content, nickel chrome alloy and a clean-up agent carried by the support consisting of a composition containing barium, aluminum, and one or more metals of the fourth group elements.

2. A getter assembly comprising a support formed of low iron content, nickel chrome alloy and a clean-up agent carried by the support consisting of a composition of 35% barium, 40% aluminum, and 25% titanium.

3. A getter assembly comprising a support formed of low iron content, nickel chrome alloy and a clean-up agent carried by the support consisting of a composition containing 30-40% barium, 3040% aluminum and 1040% titanium.

4. A getter assembly comprising a support formed of low iron content, nickel chrome alloy and a clean-up agent carried by the support consisting of a composition containing 30-40% barium, 3040% aluminum and 10-40% zirconium.

5. A getter assembly comprising a support formed of low iron content, nickel chrome alloy and a clean-up agentcarried b the support consisting of a composition containing 31% barium, 31% aluminum, 17% titanium, 14% nickel, and 7% chromium.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,898 Schickerling Oct. 16, 1928 1,797,131 De Boer Mar 17, 1931 2,043,724 Anderson June 9, 1936 2,283,189 Cox May 19, 1942 2,316,127 King Apr. 6, 1943 2,421,984 Bobrow June 10, 1947 2,528,547 Reilly et a1. Nov. 7, 1950 

5. A GETTER ASSEMBLY COMPRISING A SUPPORT FORMED OF LOW IRON CONTENT, NICKEL CHROME ALLOY AND A CLEAN-UP AGENT CARRIED BY THE SUPPORT CONSISTING OF A COMPOSITION CONTAINING 31% BARIUM, 31% ALUMINUM, 17% TITANIUM, 14% NICKEL, AND 7% CHROMIUM. 